User Manual

Table Of Contents
Tips for Properly Shooting a Color Chart
The results you get using Color Match are completely dependent on how the charts were shot
in the field. If the charts were properly shot, you’ll get great results. If the charts were improperly
shot, the results will be unpredictable.
To get the best results using Color Match, adhere to the following guidelines:
The chart must be lit evenly such that the lighting on each patch is the same intensity
(level) and color. Any shadows or changes in lighting color across the chart will result
in Color Match trying to compensate for these changes, and an inaccurate match will
result. When viewing a chart being lit prior to a shoot shooting via a waveform monitor,
the top of each individual patch as seen on the scope should appear as a rectangle
with a “flat top.
(Left) Poorly lit chart with irregularly topped waveforms,
(Right) Well lit chart with flat-topped waveforms
No patches on the chart should be clipped in any of the RGB color channels. A clipped
channel will force Color Match to use incorrect RGB values, and the resulting match will
be inaccurate.
The white patch on the recorded chart should be captured between 7095 IRE.
Correct exposure is essential to getting a good result, and while Color Match does
allow for some adjustment via the White Level option, this will only give accurate results
if the original chart is shot so that the white patch sits within the 70–95 IRE range when
viewed on a waveform monitor. It is not recommended that a white patch be shot with
a signal level above 95 IRE, since this usually means that one of the RGB channels is
close to or actually clipping which will cause an inaccurate match.
The Source Gamma setting must be set to match the encoded OETF (opto-electrical
transfer function, or gamma) of the recorded image. To be able to create an accurate
adjustment, the Color Match function requires image data that is scene linear (linear
to light). Most captured or recorded image data is encoded with a tone curve (gamma
Chapter – 116 Automated Grading Commands and Imported Grades 2630